Please show work. A. For single reactant: observe the change in rate for a chang
ID: 886401 • Letter: P
Question
Please show work.
A. For single reactant: observe the change in rate for a change in initial reactantconcentration.
The table above shows three independent reactions (not related to each other). What are the rate laws for each of thesereactions?
B. For multiple reactants: Find the reaction order for each reactant separately.
For the table above, find the rate law and the rate constant. What is the overall order of the reaction?
Reaction 1 Reaction 2 Reaction 3 [A] (M) Initial Rate (M/s) [C] (M) Initial Rate (M/s) [K] (M) Initial Rate (M/s) 0.10 0.015 0.10 0.015 0.10 0.015 0.20 0.030 0.20 0.060 0.30 0.135 0.40 0.060 0.40 0.240 0.90 1.215Explanation / Answer
From the reaction we observe that there is only one reactant in each.
Rate law :
Reaction 1 ;
Rate = k [A]m
Here k is rate constant and m is order with respect to A.
We find m by using ratio of rate for two experiment
Lets take ratio of exp 2 to exp 1
Rate 2 / rate 1 = k [A]m/ k [A]m
Here k is constant and it is cancelled since reaction is same.
Lets plug concentration of A and rate value.
0.20 / 0.10 = [0.030]m/ [0.015]m
2 = (0.030/0.015)m
2 = 2m
To calculate m we need to take ln of both side
Ln 2 = m ln 2
m = 1
so rate law becomes
Rate = k [A]
Reaction : 2
Rate = k [C]n
We use same strategy to solve for n
Rate of Exp 2 to exp 1
Rate 2 / rate 1 = ( 0.060/0.015)n
0.2/0.1 = ( 0.060/0.015)n
2 = 4n
Ln 2 = n ln 4
n = ½
Rate law becomes
Rate = k [C]1/2
Reaction 3 :
Rate law :
Rate = k [K]l
Rate 2/ rate 1 = (0.135/0.015)l
0.30/0.10 =(0.135/0.015)l
3 = 9l
Ln 3 = l ln 9
l = 1/3
Rate law
Rate = k [K]1/3
B.
Rate law :
Rate = k [A]a [ X]b
Here a and b are the orders with respect to A and B respectively.
Ex. No.
[A] (M)
[X] (M)
Initial Rate (M/s)
1
0.050
0.050
0.014
2
0.150
0.050
0.056
3
0.050
0.100
0.028
4
0.150
0.150
0.168
Lets use ratio of rate 2/ rate 1
Rate 2/ Rate 1 = (A2/A1)a x (X2/X1)b
0.056 / 0.014 = (0.150/0.050)a …concentration of X is same in both experiment so it is cancelled.
4 = 3a
We use ln
ln 4 = a ln 3
a = 1.26
Lets find for b
Rate 4/ Rate 2 = (A4/A2)a x (X4/X2)b
0.168/0.056 = (0.150 /0.050 )b
3 = 3b
b = 1
Rate law :
Rate = k [A]1.26 [X]
Calculation of rate constant
We use experiment first
0.014 = k [0.050]1.26 [0.050]
k = 12.27
Overall order : 1 + 1.26 = 2.26
Ex. No.
[A] (M)
[X] (M)
Initial Rate (M/s)
1
0.050
0.050
0.014
2
0.150
0.050
0.056
3
0.050
0.100
0.028
4
0.150
0.150
0.168